Clean fuel electric multirotor aircraft for personal air transportation and  manned or unmanned operation

ABSTRACT

Methods and systems for a full-scale vertical takeoff and landing manned or unmanned aircraft, having an all-electric, low-emission or zero-emission lift and propulsion system, an integrated ‘highway in the sky’ avionics system for navigation and guidance, a tablet-based motion command, or mission planning system to provide the operator with ‘drive by wire’ style direction control, and automatic on-board-capability to provide traffic awareness, weather display and collision avoidance. Automatic computer monitoring by a programmed triple-redundant digital autopilot computer controls each motor-controller and motor to produce pitch, bank, yaw and elevation, while simultaneously restricting the flight regime that the pilot can command, to protect the pilot from inadvertent potentially harmful acts that might lead to loss of control, or loss of vehicle stability. By using the results of the state measurements to inform motor control commands, the methods and systems contribute to the operational simplicity, reliability and safety of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to, and the benefit of, co-pending U.S.Provisional Application 61/987,009, filed May 1, 2014, for all subjectmatter common to both applications. The disclosure of said provisionalapplication is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to full-scale hybrid electric-powered(low or no emission) multirotor aircraft design, implementation andoperation. It finds particular, although not exclusive, application toon-board Fuel Cell and/or Motor/Generator powered hybrid electricmultirotor aircraft, where the motor-generator, fuel cell or otheron-board source of power transforms fuel into electricity which is thenused to operate multiple electric motors. The present invention is notdesigned for reduced scale or model aircraft, having uniquecapabilities, features, redundancy, safety and other features necessaryto the reliability and safety of on-board passengers and optionaloperators that are necessary to maintain flight-worthiness. Themultirotor aircraft may be operated in UAV or drone mode followingeither remote commands or a pre-programmed route to its destination, orit may be operated in operator mode when flown by an operator withskills equivalent to a typical automobile driver's license.

BACKGROUND

Although reduced scale multirotor aircraft (sometimes calledmulti-copters) are not new, they have been reduced scale models notintended for the rigors or requirements of carrying human passengers,and are mostly used either as toys, or for limited-duration surveillanceor aerial photography missions with motion being controlled byradio-control remotes. Most if not all are battery powered. For example,US Patent Application 20120083945 relates specifically to a reducedscale multi-copier, but does not address the safety, structural, orredundancy features necessary for an FAA-certified passenger-carryingimplementation, nor any of the systems required to implement apractical, passenger-carrying vehicle with fault-tolerance andstate-variable analysis, nor any way of generating its own power fromfuel carried on-board. The dynamics and integrity requirements ofproviding a full scale aircraft capable of safely and reliably carryinghuman passengers and operating within US and foreign airspace aresignificantly different that those of previous reduced scale models.

Therefore, a full scale multi-copter implementation that findsapplications for commuting, for recreation, for inter-citytransportation, for industrial, for delivery, or for security andsurveillance applications among others with human passengers on board,based on state-of-the-art electric motor and electronics and computertechnology with high reliability, safety, simplicity, and redundantcontrol features, with on-board capability to generate its ownelectrical power (as opposed to simply consuming energy previouslystored in electro-chemical batteries), coupled with advanced avionicsand flight control techniques is described.

A large volume of personal travel today occurs by air. For destinationsof more than 500 miles, it has historically been the fastest travel modeand, in terms of injuries per passenger mile, the safest. However, onlyabout 200 hub and spoke airports exist within the US, placing much ofthe population more than 30 minutes away from an airport. Yet there areover 5,300 small control-towered regional airports, and over 19,000small airfields with limited or no control towers throughout the US,placing more than 97% of the population within 15 to 30 minutes of anairfield. As many have noted before, this is a vastly under-utilizedcapability.

In the 21st Century, the opportunity is available to apply advancedtechnologies of the evolving National Airspace System (NAS) to enablemore-distributed, decentralized travel in the three-dimensionalairspace, leaving behind many of the constraints of the existinghub-and-spoke airport system, and the congestion of the 2-dimensionalinterstate and commuter highway systems.

Many large cities such as Boston, Houston, Los Angeles and other majormetropolitan areas are virtually gridlocked by commuter traffic, withmajor arteries already at or above capacity, and with housing andexisting businesses posing serious obstacles to widening or furtherconstruction. NASA, in its ‘Life After Airliners’ series ofpresentations (see Life After Airliners VI, EAA AirVenture 2003,Oshkosh, Wis. Aug. 3, 2003, and Life After Airliners VII, EAA AirVenture2004, Oshkosh, Wis. Jul. 30 2004) and NASA's Dr. Bruce Holmes (see SmallAircraft Transportation System—A Vision for 21st Century TransportationAlternatives, Dr. Bruce J. Holmes, NASA Langley Research Center. 2002)make the case for a future of aviation that is based on the hierarchicalintegration of Personal Air Vehicles (PAV), operating in an on-demand,disaggregated, distributed, point-to-point and scalable manner, toprovide short haul air mobility. Such a system would rely heavily on the21^(st) century integrated airspace, automation and technology ratherthan today's centralized, aggregated, hub-and-spoke system. The first,or lowest tier in this hierarchical vision are small, personal AirMobility Vehicles or aircraft, allowing people to move efficiently andsimply from point-to-any-point, without being restricted by groundtransportation congestion or the availability of high-capabilityairports. Key requirements include reduced or eliminated noise impactsto communities, vehicle automation, operations in non-radar-equippedairspace and at non-towered facilities, green technologies forpropulsion, increased safety and reliability, and en-route proceduresand systems for integrated operation within the National Airspace System(NAS) or foreign equivalents. Ultimate goals cited by NASA include anautomated self-operated aircraft, and a non-hydrocarbon-powered aircraftfor intra-urban transportation. NASA predicts that, in time, up to 45%of all future miles traveled will be in Personal Air Vehicles.

This invention addresses part of the core vision established by NASA,and documents the concept and design of an clean-fueled, electricmultirotor vehicle, referred to herein as a multirotor aircraft, or ane-copter, or an Air Mobility Vehicle, as one part of the On-Demand,Widely Distributed Point-to-Any Point 21^(st) Century Air Mobilitysystem. Operation of the vehicle is simple and attractive to manyoperators when operating under Visual Flight Rules (VFR) in Class E orClass G airspace as identified by the Federal Aviation Administration,thus in most commuter situations not requiring any radio interactionswith Air Traffic Control towers.

SUMMARY

The present invention relates to a full-scale vertical takeoff andlanding manned or unmanned aircraft having a lightweight airframecontaining a system to generate electricity from fuels such as LPG, CNG,or hydrogen, an electric lift and propulsion system mounted to alightweight multirotor upper truss or frame structure, counter-rotatingpairs of AC or DC brushless electric motors each driving a propeller orrotor, an integrated ‘highway in the sky’ avionics system fornavigation, a redundant autopilot system to manage motors and maintainvehicle stability, a tablet-computer-based mission planning and vehiclecontrol system to provide the operator with the ability to pre-plan aroute and have the system fly to the destination via autopilot or todirectly control thrust, pitch, roll and yaw through movement of thetablet computer, and ADSB or ADSB-like capability to provide traffic andsituational awareness, weather display and collision avoidance warnings.Power is provided by one or more on-board motor-generators forgenerating electrical voltage and current, or an on-board fuel cell forgenerating electrical voltage and current, electronics to monitor andcontrol electrical generation, and motor controllers to control thecommanded voltage and current to each motor and to measure itsperformance (which may include such metrics as resulting RPM, current,torque and temperature among others). As a multirotor electric aircraft,the vehicle does not fall into the standard ‘fixed wing’ or ‘helicopter’or “lighter-than-air” categories, and may require a new classificationscheme in coordination with the Federal Aviation Administration andforeign regulatory authorities.

The vehicle has no tail rotor, and lift is provided by pairs of smallelectric motors driving directly-connected pairs of counter-rotatingpropellers, also referred to as rotors. The use of counter-rotatingpropellers on each pair of motors cancels out the torque that wouldotherwise be generated by the rotational inertia. Automatic computermonitoring by a programmed redundant digital Autopilot Computer controlspitch, bank, yaw and elevation, while simultaneously using on-boardinertial sensors to maintain vehicle stability and restrict the flightregime that the pilot or route planning software can command, to protectthe vehicle from inadvertent steep bank or pitch, or other potentiallyharmful acts that might lead to loss of control. Sensed parameter valuesabout vehicle state are used to detect when recommended vehicleoperating parameters are about to be exceeded. By using the feedbackfrom vehicle state measurements to inform motor control commands, and byvoting among redundant autopilot computers, the methods and systemscontribute to the operational simplicity, stability, reliability andsafety of the vehicle.

Among the many uses for this class of vehicle are the next generation ofpersonal transportation including commuting, local travel, air taxi, andrecreation where operators need not have the level of piloting skillsnecessary for more complex, traditional aircraft or helicopters. Thisevolution is referred to as Personal Air Vehicles (PAY) or Air MobilityVehicles (AMV). The vehicle also has autonomous or unmanned applicationto aerial surveillance, security and reconnaissance, policing, andpackage or supplies delivery that will be of utility to law enforcement,border patrol, military surveillance, emergency relief aid (disasterrecovery), and commercial users.

The vehicle is equipped with redundant Autopilot Computers to acceptcontrol inputs by the operator (using the tablet computer's motion tomimic throttle and joystick commands) and manage commands to theelectric motor controllers, advanced avionics and GPS equipment toprovide location, terrain and ‘highway in the sky’ displays, and asimplified, game-like control system that allows even casual users tomaster the system after a brief demonstration flight. A tablet-computerprovides mission planning and vehicle control system capabilities togive the operator the ability to pre-plan a route and have the systemfly to the destination via autopilot, or manually control thrust, pitch,roll and yaw through movement of the tablet computer itself. Controlinputs can alternatively be made using a throttle for vertical lift(propeller RPM) control, and a joystick for pitch (nose up/down angle)and bank (angle to left or right) control, or a 3-axis joystick tocombine pitch, bank and thrust in a single control element, depending onuser preferences. The Motor Management Computer measures control inputsby the operator or autopilot directions, translates this into commandsto the controllers for the individual electric motors according to aknown performance table, then supervises motor reaction to saidcommands, and monitors vehicle state data (pitch, bank, yaw, pitch rate,bank rate, yaw rate, vertical acceleration, lateral acceleration,longitudinal acceleration, GPS speed, vertical speed air speed and otherfactors) to ensure operation of the vehicle remains within the desiredenvelop.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIG. 1 shows a block diagram showing apparatus for practicing thepresent invention;

FIG. 2 shows a detailed block diagram, detailing the key features of theredundant Motor Management Computer and voting in relation to theoverall system;

FIG. 3 shows a more detailed block diagram, focused on thefault-tolerant, triple-redundant voting control and communicationsmeans;

FIG. 4 illustrates one way in which the multiple (typically one permotor plus one each for any other servo systems) command stream outputsfrom the three autopilot computers can be voted to produce a single setof multiple command streams, using the system's knowledge of eachautopilot's internal health and status;

FIG. 5 shows a flow chart that illustrates the present invention inaccordance with one example embodiment;

FIG. 6 shows an example of a type of 3^(rd)-party display presentationused to present data necessary to the ‘highway in the sky’ operation ofthe system of FIG. 1;

FIG. 7 shows an example of a mission control tablet computer used toplan the vehicle's route between origin and destination, using GPScoordinates and altitudes to implement waypoints, which provides datadescribing the route and mission to autopilot computers, which thenimplement the mission when authorized;

FIG. 8 shows electrical and systems connectivity of various controlinterface components of a system of the invention;

FIG. 9 shows electrical and systems connectivity of various motorcontrol components of a system of the invention;

FIG. 10 shows a view of an aircraft in accordance with an embodiment ofthe present invention; and

FIG. 11 shows an alternate view of the truss structure the aircraft ofFIG. 10.

DETAILED DESCRIPTION

To provide an overall understanding, certain illustrative embodimentswill now be described; however, it will be understood by one of skill inthe art that the systems and methods described herein can be adapted andmodified to provide systems and methods for other suitable applicationsand that other additions and modifications can be made without departingfrom the scope of the systems and methods described herein.

Unless otherwise specified, the illustrated embodiments can beunderstood as providing exemplary features of varying detail of certainembodiments, and therefore, unless otherwise specified, features,components, modules, and/or aspects of the illustrations can beotherwise combined, separated, interchanged, and/or rearranged withoutdeparting from the disclosed systems or methods.

FIG. 1 depicts in block diagram form one type of system that may beemployed to carry out the present invention's teachings. Here, this one-to two-person personal aerial vehicle (PAV) or unmanned aerial vehicle(UAV) includes on-board equipment such as a primary flight displays 12,an Automatic Dependent Surveillance-B (ADSB) transmitter/receiver 14, aglobal-positioning system (GPS) receiver typically embedded within 12, afuel gauge 16, an air data computer to calculate airspeed and verticalspeed 38, mission control tablet computers 36 and mission planningsoftware 34, and redundant flight computers (also referred to asautopilot computers 32), all of which monitor either the operation andposition of the aircraft or monitor and control the engines andgenerator-sets and fuel systems and provide display presentations thatrepresent various aspects of those systems' operation and the aircraft'sstate data, such as altitude, attitude, ground speed, position, localterrain, recommended flight path, weather data, remaining fuel andflying time, motor voltage and current status, intended destination, andother information necessary to a successful and safe flight. The engineand generator set may readily be replaced by a hydrogen-powered FuelCell subsystem to generate electricity, where the fuel cell subsystemcombines stored hydrogen with compressed air to generate electricitywith a byproduct of only water and heat, thereby forming an engine andgenerator set or fuel cell 18. The engine and generator set or fuel cell18 can also include a fuel pump and cooling system 44 and an enginesupercharger 46 to optimize the efficiency and/or performance of theengine and generator set or fuel cell 18. As would be appreciated by oneskilled in the art, the engine and generator set may also be replaced bya battery subsystem, consisting of high-voltage battery array, batterymonitoring and charger subsystem, though such a configuration would notbe fuel cell based. This disclosure is meant to address both kinds ofpower generation systems as well as stored-energy battery systems. Forpurposes of illustration, the present description focuses on a fuel cellform of electricity generation.

Vehicle state (pitch, bank, airspeed, vertical speed and altitude) arecommanded a) by the operator using either a1) physical motions andcommands made using the mission control tablet computers 36 as an inputdevice; or a2) pre-planned mission routes selected and pre-programmedusing the mission control tablets 36 and mission-planning software 34,or b) in UAV mode using pre-planned mission routes selected andpre-programmed using the mission control tablet computers 36 andmission-planning software 34. In either case, the mission control tabletcomputer 36 transmits the designated route or position command set toautopilot computers 32 and voter 42 over a serial datalink (in thisexample, using a repeating series of servo control pulses carrying thedesignated command information, represented by pulse-widths varyingbetween 1.0 to 2.0 milliseconds contained within a ‘frame’ of, forexample, 10 to 30 milliseconds). Multiple ‘channels’ of command data maybe included within each ‘frame’, with the only caveat being that eachmaximum pulse width must have a period of no output (typically zerovolts or logic zero) before the next channel's pulse can begin. In thisway, multiple channels of command information are multiplexed onto asingle serial pulse stream within each frame. The parameters for eachpulse within the frame are that it has a minimum pulse width, a maximumpulse width, and a periodic repetition rate. The motor's RPM isdetermined by the duration of the pulse that is applied to the controlwire. Note that the motor's RPM is not determined by the duty cycle orrepetition rate of the signal, but by the duration of the designatedpulse. The autopilot might expect to see a pulse every 20 ms, althoughthis can be shorter or longer, depending upon system requirements. Thewidth of each channel's pulse within the frame will determine how fastthe corresponding motor turns. For example, anything less than a 1.2 mspulse might be pre-programmed as ‘Motor OFF’ or 0 RPM, and pulse widthsranging from 1.2 ms up to 2.0 ms will proportionately command the motorfrom 20% RPM to 100% RPM. Given the physical constraints of the motorbeing controlled, the exact correlation between pulse width andresultant motor RPM will be a function of each system's programming.

The receiver at each autopilot then uses software algorithms totranslate the received channel pulses correlating to channel commandsfrom the tablet computer or alternate control means (in this example theset of pulse-widths representing the control inputs such as pitch, bankand yaw and rpm) into the necessary outputs to control each of themultiple (in this example six) motor controllers 24, motors, andpropellers 29 to achieve the commanded vehicle motions. Commands mightbe transmitted by direct wire, or over a secure RF (wireless) signalbetween transmitter and receiver. The autopilot is also responsible formeasuring other vehicle state information, such as pitch, bank angle,yaw, accelerations, and for maintaining vehicle stability.

The command interface between the autopilots and the multiple motorcontrollers 24 will vary from one equipment set to another, and mightentail such signal options to each motor controller 24 as a variable DCvoltage, a variable resistance, a CAN or other serial network command,an RS-232 or other serial data command, or a PWM (pulse-width modulated)serial pulse stream, or other interface standard obvious to one skilledin the art. Control algorithms operating within the autopilot computer32 perform the necessary state analysis, comparisons, and generateresultant commands to the individual motor controllers 24 and monitorthe resulting vehicle state and stability. A voting means 42 decideswhich two of three autopilot computers 32 are in agreement, andautomatically performs the voting operation to connect the properautopilot computer 32 outputs to the corresponding motor controllers 24.

In an alternate control embodiment, the commanded vehicle motion andengine rpm commands could also be embodied by a pair of joysticks and athrottle, similar to those used to control radio-controlled aircraft, oreven by a traditional sidearm controller and throttle, similar to anautomotive foot pedal, where the joysticks/sidearm controller andthrottle provide readings (which could be potentiometers, hall-effectsensors, or rotary-variable differential transformers (RVDT)) indicativeof commanded motions which may then be translated into the appropriatemessage format and transmitted to the autopilot computers 32, andthereby used to control the multiple motors and propellers 29. Thesidearm controller or joystick could also be embodied in a ‘steeringwheel’ or control yoke capable of left-right and fore-aft motion, wherethe 2-axis joystick or control yoke provides two independent sets ofsingle- or dual-redundant variable voltage or potentiometer settingsindicative of pitch command (nose up or nose down) and bank command(left side up or left side down).

Motors of the multiple motors and propellers 29 in the preferredembodiment are brushless synchronous three-phase AC or DC motors,capable of operating as an aircraft motor, and that are eitherair-cooled or liquid cooled or both.

Throughout all of the system operation, controlling and operating thevehicle is performed with the necessary safety, reliability, performanceand redundancy measures required to protect human life to acceptedflight-worthiness standards.

Electrical energy to operate the vehicle is derived from theengine-generator sets or fuel cells 18, which provide voltage andcurrent to the motor controllers 24 through high-current diodes or FieldEffect Transistors (FETs) 20 and circuit breakers 902 (shown in greaterdetail in FIG. 9). High current contactors 904 are engaged anddisengaged under control of the vehicle key switch 40, similar to acar's ignition switch, which applies voltage to the starter/generator 26to start the engine-generators and produce electrical power. Forexample, the high current contactors 904 are essentially large vacuumrelays that are controlled by the vehicle key switch 40 and enable thecurrent to flow to the starter/generator 26. In accordance with anexample embodiment of the present invention, the starter/generator 26also supplies power to the avionic systems of the aircraft. The motorcontrollers 24 each individually manage the necessary voltage andcurrent to achieve the desired RPM and torque (collectively, thrust)produced by each motor and propeller combination 28. The number of motorcontrollers 24 and motor/propeller combinations 28 per vehicle may be asfew as 6, and as many as 16 or more, depending upon vehiclearchitecture, desired payload (weight), fuel capacity, electric motorsize, weight, and power, and vehicle structure. Advantageously,implementing a multirotor vehicle having a plurality of independentmotor controllers 24 and motors, allows the use of smaller motors withlower current demands, such that fuel cells can produce the necessaryvoltage and current at a total weight for a functional aviation vehiclewhile achieving adequate flight durations.

The engines and generator sets or fuel cells 18 are fed by on-board fuelstorage 22. The ability to refuel the multirotor aircraft's tanks at theorigin, at the destination, or at roadside refueling stations isfundamental to the vehicle's utility and acceptance by the commutingpublic. Advantageously, the ability to refuel the fuel storage tanks toreplace the energy source for the motors reduces the downtime requiredby conventional all electric vehicles (e.g., battery operated vehicles).Variations are included that will operate from Compressed Natural Gas(CNG), Liquid Petroleum Gas (LPG), AvGas (typical aviation fuel), and/orHydrogen (for the fuel-cell versions). As would be appreciated by oneskilled in the art, the engine and generator sets 18 can be powered byLPG, CNG, or AvGas fuel, or fuel cells 18 can be powered by hydrogen.Accordingly, the engine and generator sets or fuel cells 18 can createelectricity from fuel to provide power to the motors on the multirotoraircraft. Advantageously, the use of engine and generator sets or fuelcells 18 are more weight efficient than batteries and store a greaterenergy density than existing Li ion batteries, thereby reducing the workrequired by the motors to produce lift. Additionally, the use ofhydrogen fuel cells, LPG, CNG, or AvGas reduces the amount of workrequired by the motors due to the reduced weight as the fuel isconsumed.

Due to the nature of the all-electric multirotor vehicle, it is alsopossible to carry an on-board high-voltage battery and rechargingsubsystem in place of engine and generator sets or fuel cells 18, withan external receptacle to facilitate recharging the on-board batteries.In some instances it may also be desirable to operate the vehicle at theend of an electrical and data tether, for long-duration unmannedairborne surveillance, security or other applications. In thissituation, power would be replenished or provided via the tether cable,and control information could be provided either by onboard systems asdescribed herein, or by bidirectional wired or broadband or wireless orRF networks operated by ground controllers.

Power to operate the vehicle's avionics 12, 14, 16, 32, 34, 36, 38 andsupport lighting is provided by either a) a low-voltagestarter-generator 26 powered by the engine and generator sets or fuelcells 18 and providing power to avionics battery 27, or b) a DC to DCConverter providing energy to Avionics Battery 27. If the DC to DCConverter is used, it draws power from high-voltage produced by theengine and generator sets or fuel cells 18 and down-converts the highervoltage, typically 300V DC to 600 VDC in this embodiment, to either 24Vor 28V standards, either of which are voltages typically used in smallaircraft systems. Navigation, Strobe and Landing lights draw power from26 and 27, and provide necessary aircraft illumination for safety andoperations at night under US and foreign airspace regulations. Suitablecircuit breaker 902 and switch means are provided to control theseancillary lighting devices as part of the overall system.

Pairs of motors for the multiple motors and propellers 29 are commandedto operate at different RPM settings to produce slightly differingamounts of thrust under autopilot control, thus imparting a pitchmoment, or a bank moment, or a yaw moment, or a change in altitude, orsimultaneously all of the above to the aircraft, using position feedbackfrom the autopilot's 6-axis inertial sensors to maintain stable flightattitude. Sensor data is read by each autopilot to assess its physicalmotion and rate of motion, which is then compared to commanded motion inall three dimensions to assess what new motion commands are required.

Of course, not all aircraft will employ the same mix of avionics,instrumentation or controllers or motors, and some aircraft will includeequipment different from this mix or in addition to this mix. Not shownfor example are radios as may be desirable for communications or othersmall ancillary avionics customary in general aviation aircraft of thissize. Whatever the mix is, though, some set of equipment accepts inputcommands from an operator, translates those input commands intodiffering thrust amounts from the pairs of counter-rotating motors andpropellers 29, and thus produces pitch, bank, yaw, and vertical motionof the aircraft using electric motors. When combined with avionics,instrumentation and display of the aircraft's current and intendedlocation, the set of equipment enables the operator to easily and safelyoperate and guide the aircraft to its intended destination.

The autopilot computer 32 is embodied in a microprocessor-based circuitand includes the various interface circuits required to communicate withthe aircraft's data busses, multi-channel servo controllers (inputs) 35and 37, and motor controller (outputs) 24, and to take inertial andattitude measurements to maintain stability. This is further detailed inFIG. 2. In addition, autopilot computer 32 may also be configured forautomatic recording or reporting of aircraft position, aircraft statedata, velocity, altitude, pitch angle, bank angle, thrust, and otherparameters typical of capturing aircraft position and performance, forlater analysis or playback. To accomplish these requirements, saidautopilot contains an embedded air data computer (ADC) and embeddedinertial measurement sensors, although these data could also be derivedfrom small, separate stand-alone units. The autopilot may be operated asa single or dual controller, but for reliability and safety purposes,the preferred embodiment uses a triple redundant autopilot, where theunits share information, decisions and intended commands in aco-operative relationship using one or more networks (two are preferred,for reliability and availability). In the event of a seriousdisagreement outside of allowable guard-bands, and assuming three unitsare present, a 2-out-of-3 vote determines the command to be implementedby the motor controllers 24, and the appropriate commands areautomatically selected and transmitted to the motor controllers 24. Theoperator is not typically notified of the controller disagreement duringflight, but the result will be logged so that the units may be scheduledfor further diagnostics post-flight.

The mission control tablet computer 36 is typically a dual redundantimplementation, where each mission control tablet computer 36 containsidentical hardware and software, and a screen button designating thatunit as ‘Primary’ or ‘Backup’. The primary unit is used in all casesunless it has failed, whereby either the operator (if present) mustselect the ‘Backup’ unit through a touch icon, or an automatic fail-overwill select the Backup unit when the autopilots detect a failure of thePrimary. When operating without a formal pre-programmed route, themission control tablet computer 36 uses its internal motion sensors toassess the operator's intent, and transmits the desired motion commandsto the autopilot. In UAV mode, or in manned automatic mode, the missionplanning software 34 will be used pre-flight to designate a route,destination, and altitude profile for the aircraft to fly, forming theflight plan for that flight. Flight plans, if entered into the Primarymission control tablet computer 36, are automatically sent to thecorresponding autopilot, and the autopilots automatically cross-fill theflight plan details between themselves and the Backup mission controltablet computer 36, so that each autopilot computer 32 and missioncontrol tablet computer 36 carries the same mission commands andintended route. In the event that the Primary tablet fails, the Backuptablet already contains the same flight details, and assumes control ofthe flight once selected either by operator action or automaticfail-over.

For motor control of the multiple motors and propellers 29, there arethree phases that connect from each high-current controller to eachmotor for a synchronous AC or DC brushless motor. Reversing the positionof any two of the 3 phases will cause the motor to run the oppositedirection. There is alternately a software setting within the motorcontroller 24 that allows the same effect, but it is preferred tohard-wire it, since the designated motors running in the oppositedirection must also have propellers with a reversed pitch (these aresometimes referred to as left-hand vs right-hand pitch, or puller(normal) vs pusher (reversed) pitch propellers, thereby forming themultiple motors and propellers 29. Operating the motors incounter-rotating pairs cancels out the rotational torque that wouldotherwise be trying to spin the vehicle.

In the illustrated embodiment, the operational analyses and controlalgorithms that will shortly be described are performed by the on-boardautopilot computer 32, and flight path and other useful data arepresented on the dual avionics displays 12. Various aspects of theinvention can be practiced with a different division of labor; some orall of the position and control instructions can in principle beperformed outside the aircraft, in ground-based equipment, by using abroadband or 802.11 Wi-Fi network or Radio Frequency (RF) data-linkbetween the aircraft and the ground-based equipment.

For the illustrative embodiment of FIG. 1, the representation of thehighway in the sky display may include, for example, wickets orgoal-posts appearing to fade into the depth of the display screen,thereby signifying where the aircraft is intended to fly. Othercombinations of display graphics and terrain representations, as well asaudible signals may be used to convey this or other information and/orwarnings to the operator in whatever manner is most effective. Forexample, combinations of graphical depictions or audible messages couldbe used to indicate that the aircraft is being asked to depart outsideof certain predetermined “cruise” or “intended” conditions, while theMotor Management Computer makes adjustments so as not to violate thoseintended conditions. As will be seen below, operating the aircraftwithin “cruise” or “intended” conditions serves the purpose ofprotecting the aircraft and the operator from unintended deviations ordeparture from safe flight. The goal of the ‘highway in the sky’presentation is to enable an operator to select their destination, andthen use the tablet computer as an input device to drive or guide thevehicle along the prescribed path to the destination.

The combination of the avionics display system coupled with the ADSBcapability enables the multirotor aircraft to receive broadcast datafrom other nearby aircraft, and to thereby allow the multirotor aircraftto avoid close encounters with other aircraft; to broadcast own-aircraftposition data to avoid close encounters with other cooperating aircraft;to receive weather data for display to the pilot and for use by theavionics display system within the multirotor aircraft; to allowoperation of the multirotor aircraft with little or no requirement tointeract with or communicate with air traffic controllers; and toperform calculations for flight path optimization, based uponown-aircraft state, cooperating aircraft state, and available flightpath dynamics under the National Airspace System, and thus achieveoptimal or near-optimal flight path from origin to destination.

FIG. 3 is a diagram showing the voting process that is implemented toperform the qualitative decision process. Since there is no one concise‘right answer’ in this real-time system, the autopilot computers 32instead share flight plan data and the desired parameters for operatingthe flight by cross-filling the flight plan, and each measures its ownstate-space variables that define the current aircraft state, and thehealth of each Node. Each node independently produces a set of motorcontrol outputs (in serial PWM format in the described embodiment), andeach node assesses its own internal health status. The results of thehealth-status assessment are then used to select which of the autopilotsactually are in control of the motors of the multiple motors andpropellers 29.

The voting process is guided by the following rules:

Each autopilot node (AP) 32 asserts “node ok” 304 when its internalhealth is good, at the start of each message. Messages occur each updateperiod, and provide shared communications between AP's.

-   -   Each AP de-asserts “node ok” if it detects an internal failure,        or its internal watchdog timer expires (indicating AP failure),        or it fails background self-test    -   Each AP's “node ok” signal must pulse at least once per time        interval to retrigger a 1-shot ‘watchdog’ timer 306.    -   If the AP's health bit does not pulse, the watchdog times out        and the AP is considered invalid.    -   Each AP connects to the other two AP's over a dual redundant,        multi-transmitter bus 310. This may be a can network, or an        RS-422/423 serial network, or an Ethernet network, or similar        means of allowing multiple nodes to communicate.    -   The AP's determine which is the primary AP based on which is        communicating with the cockpit primary tablet.    -   The primary AP receives flight plan data or flight commands from        the primary tablet.    -   The AP's then crossfill flight plan data and waypoint data        between themselves using the dual redundant network 310. This        assures each autopilot (AP) knows the mission or command        parameters as if it had received them from the tablet.    -   In the cockpit, the backup tablet receives a copy of the flight        plan data or flight commands from its crossfilled AP.    -   Each AP then monitors aircraft state vs commanded state to        ensure the primary AP is working, within an acceptable tolerance        or guard-band range. Results are shared between AP's, using the        dual redundant network 310.    -   Motor output commands are issued using the PWM motor control        serial signals, in this embodiment. Other embodiments have also        been described but are not dealt with in detail here. Outputs        from each AP pass through the voter 312 before being presented        to each motor controller 24.    -   If an AP de-asserts its health bit or fails to retrigger its        watchdog timer, the AP is considered invalid and the voter 312        automatically selects a different AP to control the flight based        on the voting table.    -   The new AP assumes control of vehicle state and issues motor        commands to the voter 312 as before.    -   Each AP maintains a health-status state table for its companion        AP's. If an AP fails to communicate, it is logged as        inoperative. The remaining AP's update their state table and        will no longer accept or expect input from the failed or failing        AP    -   Qualitative analysis is also monitored by the AP's that are not        presently in command.    -   Each AP maintains its own state table plus 2 other state tables        and an allowable deviation table.    -   The network master issues a new frame to the other AP's at a        periodic rate, and then publishes its latest state data.    -   Each AP must publish its results to the other AP's within a        programmable delay after seeing the message frame, or be        declared invalid.    -   If the message frame is not received after a programmable delay,        node 2 assumes network master role and sends a message to node 1        to end its master role.

Note that the redundant communication systems are provided in order topermit the system to survive a single fault with ne degradation ofsystem operations or safety.

Multi-way analog switch 312 monitors the state of 1.OK, 2.OK and 3.OKand uses those 3 signals to determine which serial signal set 302 toenable so that motor control messages may pass between the controllingnode and the motor controllers 24. This motor controller 24 serial busis typified by a PWM pulse train in the preferred embodiment, althoughother serial communications may be used such as RS-232, CAN, or asimilar communications means. In a preferred embodiment, the PWM pulsetrain is employed; with the width of the PWM pulse on each channel beingused to designate the percent of RPM that the motor controller 24 shouldachieve. This enables the controlling node to issue commands to eachmotor controller 24 on the network. FIG. 4 provides additional detail onthe voting and signal switching mechanism in one embodiment of thetechnique.

FIG. 5 is a flowchart that depicts in simplified form ameasurement-analysis-adjustment-control approach that some embodimentsof the invention may employ. The system enters the routine 400periodically, at every “tick” of a periodic system frame as initiated bythe controlling AP via an output message. The frequency at which thisoccurs is selected to be appropriate to the parameters being sensed andthe flight dynamics of the vehicle, and in some cases the frequenciesmay be different for different measurements. For the sake of simplicity,though, the frequency is the same for all of them, and, for the sake ofconcreteness, we apply an oversampling frequency of forty times persecond or every 25 milliseconds, more or less.

As block 402 in FIG. 5 indicates, the system first takes measurements ofvarious sensor outputs indicative of each motor's performance of themultiple motors and propellers 29, including propeller RPM, motorvoltage, motor current and (if available) temperature. In this system,such measurement data may be readily accessed through each motorcontroller's 24 serial data busses, and the illustrated embodimentselects among the various available measurement parameters that can beobtained in this manner.

With the motor data thus taken, the system performs various analyses, asat block 404, which may be used to calculate each motor's thrust andcontribution to vehicle lift and attitude. Block 406 then measures thethrottle command, by detecting where the tablet throttle command orthrottle lever has been positioned by the operator and notes any changein commanded thrust from prior samples.

Block 408 measures the voltage, current drawn, and estimated remainingfuel. This data is then used as part of the analysis of remaining flightduration for the trip or mission underway and is made available to theoperator.

As block 410 in FIG. 5 indicates, the autopilot computer 32 gathers arepresentative group of aircraft measurements from other embeddedinertial sensors and (optionally) other onboard sensors including airdata sensors, and GPS data derived by receiving data from embedded GPSreceivers. Such measurements may include air speed, vertical speed,pressure altitude, GPS altitude, GPS latitude and GPS longitude,outside-air temperature (OAT), pitch angle, bank angle, yaw angle, pitchrate, bank rate, yaw rate, longitudinal acceleration, lateralacceleration, and vertical acceleration.

For some of the parameters, there are predetermined limits with whichthe system compares the measured values. These may be limits on thevalues themselves and/or limits in the amount of change since the lastreading or from some average of the past few readings.

Block 412 then measures the tablet flight controller command, bydetecting where the tablet has been positioned by the operator in twoaxis (pitch-bank) space and notes any change in commanded pitch-bankposition from prior samples. If operating in pre-planned (UAV) mode,Block 412 assesses the next required step in the pre-planned missionpreviously loaded to the autopilot.

Block 414 then assimilates all of the vehicle state data and commandeddata from the operator, and calculates the intended matrix of motorcontroller 24 adjustments necessary to accommodate the desired motions.Block 416 then executes the background health-status tests, and passesthe command matrix on to block 418. If the background health-status testfails, Block 416 reports the error, and disables the voter 312 outputstate bit. If the test itself cannot be run, the voter 312 output statebit(s) will cease to pulse, and the external watchdog will declare thefailure of that controller, allowing another to take over through theexternal voter 312 action.

Block 418 in turn examines the intended matrix of commands, and assesseswhether the intended actions are within the aircraft's safety margins.For example, if motor controller 3 is being commanded to output acertain current, is that current within the approved performance metricsfor this aircraft. If not, block 420 makes adjustments to the matrix ofmotor controller 24 commands, and provides an indication to the Displayto indicate that vehicle performance has been adjusted or constrained.

Similarly, Block 422 examines the intended matrix of commands, andassesses whether the electrical system and fuel tank contain sufficientpower to accomplish the mission with margins and without compromisingthe overall success of the mission. For example, if all motorcontrollers 24 are being commanded to output a higher current toincrease altitude, is that current available and can this be donewithout compromising the overall success of the mission. If not, block424 makes adjustments to the matrix of motor controller 24 commands, andprovides an indication to the Display to indicate that vehicleperformance has been adjusted or constrained.

Block 424 then issues network messages to indicate its actions andstatus to the other autopilot nodes.

Block 426 then issues the commands to the motor controllers 24, andmonitors their responses for correctness.

Block 428 then captures all of the available aircraft performance andstate data and determines whether it is time to store an update sampleto a non-volatile data storage device, typically a flash memory deviceor other form of permanent data storage. Typically samples are storedonce per second, so the system need not perform the storage operation atevery 100 millisecond sample opportunity.

Block 430 then provides any necessary updates to the operator Display,and returns to await the next tick, when the entire sequence isrepeated.

When the flight is complete, the operator or his maintenance mechaniccan then tap into the recorded data and display it or play it back in avariety of presentation formats. One approach would be for the onboarddisplay apparatus to take the form of computers so programmed as toacquire the recorded data, determine the styles of display appropriateto the various parameters, provide the user a list of views among whichto select for reviewing or playing back (simulating) the data, anddisplaying the data in accordance with those views. However, althoughthe illustrated embodiment does not rely on ground apparatus to providethe display, this could also be accomplished by an off-board or grounddisplay or remote server system. The system does so by utilizing aso-called client-server approach where the on-board apparatus (dataserver) prepares and provides web pages; the ground display apparatusrequires only a standard web-browser client to provide the desired userinterface.

FIG. 6 depicts one kind of display presentation 502 that can be providedto show weather data (in the bottom halt) and highway in the sky data(in the top half). Also shown are the vehicle's GPS airspeed (upper leftvertical bar) and GPS altitude (upper right vertical bar). Magneticheading, bank and pitch are also displayed, to present the operator witha comprehensive, 3-dimensional representation of where the aircraft is,how it is being operated, and where it is headed. Other screens can beselected from a touch-sensitive row of buttons along the lower portionof the screen. Display presentation 504 is similar, but has added‘wickets’ to guide the pilot along the flight path. The lower half ofthe screen illustrates nearby landing sites that can readily be reachedby the vehicle with the amount of power on board. Said display isnotionally a software package installed and operating on a ‘tablet’computer, most probably an Apple iPad. The use of two identical iPadsrunning identical display software allows the user to configure severaldifferent display presentations, and yet still have full capability inthe event that one display should fail during a flight. This enhancesthe vehicle's overall safety and reliability.

In addition to providing a browser-based communications mode, theon-board system also enables stored data to be read in other ways. Forexample, the on-board storage may also be examined and/or downloadedusing a web server interface. Typically, but not necessarily, theon-board storage contains the data in a comma-delimited or other simplefile format easily read by employing standard techniques.

The memory device typically has enough capacity to store data forthousands of hours—possibly, the aircraft's entire service history—somaintenance personnel may be able to employ a ground-based display toshow data not only for the most recent flight but also for someselection of previous data, such as the most-recent five flights, theprevious ten flight hours, all data since the last overhaul, the lasttwo hundred hours, or the entire service history, together withindications highlighting any anomalies.

The present invention's approach to multirotor vehicle operation andcontrol, coupled with its onboard equipment for measuring, analyzing,displaying and predicting motor and controller items that can beadjusted, and for calculating whether the commanded motion is safe andwithin the vehicle's capabilities, can significantly enhance the safetyand utility of this novel aircraft design, and reduce the probability ofa novice operator attempting to operate outside of the vehicle's normaloperational limits. It therefore constitutes a significant advance inthe art. Similarly, the ability of the vehicle to operate underpre-planned mission parameters through a triple-redundant autopilotsignificantly enhances the safety and utility of this novel aircraftdesign, and protects the operator or payload to the greatest extentpossible. The design is such that any single failure of a motor,controller, or autopilot or tablet is automatically managed andcircumvented, to ensure the safe continued operation and landing of thevehicle.

FIG. 7 shows the mission control tablet computer 36. This tablet and itssoftware allow the operator to guide and control operation of themulti-copter by tilting the tablet, and adjusting throttle settingsusing a touch-slider. The software can be operated as Primary or Backup,in coordination with the triple-redundant autopilot software describedpreviously.

FIG. 8 shows electrical connectivity of components of the controlinterface 800 components, including the primary flight displays 12, theAutomatic Dependent Surveillance-B (ADSB) transmitter/receiver 14, theair data computer to calculate airspeed and vertical speed 38, missioncontrol tablet computers 36, and redundant autopilot computers 32, thecontrollers for navigation/strobe 802, landing lights 804, and forinterior 808. As would be appreciated by one skilled in the art, thecontroller 802, 804, and 808 control naystrobes/tailstrobe lights 810,landing lights 812, and interior lights 814, respectively. Continuingwith FIG. 8, the control interface 800 components also include theredundant flight computers (e.g., autopilot computers 32) coupled viacontrollers to the eight motor controllers 24. In accordance with anexample embodiment of the present invention, the mission control tabletcomputers 36 can communicate a route or position command set to theautopilot computers 12 using a serial datalinks 816. The autopilotcomputers 12 can pass one or more motor commands based on the route orposition command set to the voter 42, as control signals. As would beappreciated by one skilled in the art, the autopilot computers 32 maycommunicate over a redundant communication network 818 during the votingprocess. Thereafter, the voter 42 can determine which signals totransmit to the motor controllers 24 based on the voting process, asdiscussed herein.

FIG. 9 shows electrical connectivity and fuel system 900 for themultirotor aircraft. The electrical connectivity includes six motor andpropeller combinations 28 (of multiple motors and propellers 29) and theelectrical components needed to supply the motor and propellercombinations with power. A high current contactor 904 is engaged anddisengaged under control of the vehicle key switch 40, which appliesvoltage to the starter/generator 26 to start the engine and generatorsets or fuel cells 18. In accordance with an example embodiment of thepresent invention, after ignition, the engine and generator sets or fuelcells 18 (e.g., one or more hydrogen-powered fuel-cells orhydrocarbon-fueled motors) create the electricity to power the six motorand propeller combinations 28 (of multiple motors and propellers 29). Apower distribution and circuit breaker 902 subsystem autonomouslymonitors and controls distribution of the generated electrical voltageand current from the engine and generator sets or fuel cells 18 to theplurality of motor controllers 24. As would be appreciated by oneskilled in the art, the circuit breaker is designed to protect each ofthe motor controllers 24 from damage resulting from an overload or shortcircuit. Additionally, the electrical connectivity and fuel system 900includes diodes or FETs 20, providing isolation between each electricalsource and an electrical main bus and the engine and generator sets orfuel cells 18. The diodes or FETs 20 are also part of the fail-safecircuitry, in that they diode-OR the current from the two sourcestogether into the electrical main bus. For example, if one of the pairof the engine and generator sets or fuel cells 18 fails, the diodes orFETs 20 allow the current provided by the now sole remaining currentsource to be equally shared and distributed to all motor controllers 24.Such events would clearly constitute a system failure, and the autopilotcomputers 32 would react accordingly to land the aircraft safely as soonas possible. Advantageously, the diodes or FETs 20 keep the system fromlosing half its motors by sharing the remaining current. Additionally,the diodes or FETs 20 are also individually enabled, so in the eventthat one motor fails or is degraded, the appropriate motor and propellercombinations 28 (of multiple motors and propellers 29)(thecounter-rotating pair) would be disabled. For example, the diodes orFETs 20 would disable the enable current for the appropriate motor andpropeller combinations 28 (of multiple motors and propellers 29) toswitch off that pair and avoid imbalanced thrust. In accordance with anexample embodiment of the present invention, the six motor and propellercombinations 28 (of multiple motors and propellers 29) each include amotor and a propeller and are connected to the motor controllers 24,that control the independent movement of the six motors of the six motorand propeller combinations. As would be appreciated by one skilled inthe art, the electrical connectivity and fuel system 900 may beimplemented using 6, 8, 10, 12, 14, 16, or more independent motorcontrollers 24 and the motor and propeller combinations 28.

Continuing with FIG. 9, the electrical connectivity and fuel system 900also depicts the redundant battery module system as well as componentsof the DC charging system. The electrical connectivity and fuel system900 includes the fuel storage 22, the avionics battery 27, the fuel pumpand cooling system 44, the engine supercharger 46, and astarter/alternator. The engines and generator sets or fuel cells 18 arefed by on-board fuel storage 22 and use the fuel to produce a source ofpower for the motor and propeller combinations 28. As would beappreciated by one skilled in the art, the engine and generator sets orfuel cells 18 can include one or more hydrogen-powered fuel-cells orhydrocarbon-fueled motors and each engine can be fueled by compressednatural gas (CNG), liquefied petroleum gas (LPG), or aviation standardfuel (avgas) and each fuel cell is powered by hydrogen or other suitablegaseous fuel.

FIG. 10 shows an aircraft 1000 in accordance with an embodiment of thepresent invention including a truss system 1010 and an aircraft body1020, and FIG. 11 shows another view of the aircraft 1000 with anenlarged view of the truss system 1010 as coupled to the frame of theaircraft body 1020 shown in FIG. 10. In accordance with an exampleembodiment of the present invention, the multiple electric motors 24 aresupported by the truss system 1010, and when the aircraft is elevated,the truss system 1010 supports (in suspension) the aircraft itself.

The methods and systems described herein are not limited to a particularaircraft or hardware or software configuration, and may findapplicability in many aircraft or operating environments. For example,the algorithms described herein can be implemented in hardware orsoftware, or a combination of hardware and software. The methods andsystems can be implemented in one or more computer programs, where acomputer program can be understood to include one or more processorexecutable instructions. The computer program(s) can execute on one ormore programmable processors, and can be stored on one or more storagemedium readable by the processor (including volatile and non-volatilememory and/or storage elements), one or more input devices, and/or oneor more output devices. The processor thus can access one or more inputdevices to obtain input data, and can access one or more output devicesto communicate output data. The input and/or output devices can includeone or more of the following: a mission control tablet computer 32,mission planning software 34 program, throttle pedal, throttle arm,sidearm controller, yoke or control wheel, or other motion-indicatingdevice capable of being accessed by a processor as provided herein,where such aforementioned examples are not exhaustive, and are forillustration and not limitation.

The computer program(s) is preferably implemented using one or more highlevel procedural or object-oriented programming languages to communicatewith a computer system; however, the program(s) can be implemented inassembly or machine language, if desired. The language can be compiledor interpreted.

As provided herein, the processor(s) can thus in some embodiments beembedded in three identical devices that can be operated independentlyin a networked or communicating environment, where the network caninclude, for example, a Local Area Network (LAN) such as Ethernet, orserial networks such as RS232 or CAN. The network(s) can be wired,wireless RF, or broadband, or a combination thereof and can use one ormore communications protocols to facilitate communications between thedifferent processors. The processors can be configured for distributedprocessing and can utilize, in some embodiments, a client-server modelas needed. Accordingly, the methods and systems can utilize multipleprocessors and/or processor devices to perform the necessary algorithmsand determine the appropriate vehicle commands, and if implemented inthree units, the three units can vote among themselves to arrive at a 2out of 3 consensus for the actions to be taken. As would be appreciatedby one skilled in the art, the voting can also be carried out usinganother number of units (e.g., one two, three, four, five, six, etc.).For example, the voting can use other system-state information to breakany ties that may occur when an even number of units disagree, thushaving the system arrive at a consensus that provides an acceptablelevel of safety for operations.

The device(s) or computer systems that integrate with the processor(s)for displaying the highway in the sky presentations can include, forexample, a personal computer with display, a workstation (e.g., Sun,HP), a personal digital assistant (PDA) or tablet such as an iPad, oranother device capable of communicating with a processor(s) that canoperate as provided herein. Accordingly, the devices provided herein arenot exhaustive and are provided for illustration and not limitation.

References to “a processor” or “the processor” can be understood toinclude one or more processors that can communicate in a stand-aloneand/or a distributed environment(s), and can thus can be configured tocommunicate via wired or wireless communications with other processors,where such one or more processor can be configured to operate on one ormore processor-controlled devices that can be similar or differentdevices. Furthermore, references to memory, unless otherwise specified,can include one or more processor-readable and accessible memoryelements and/or components that can be internal to theprocessor-controlled device, external to the processor-controlleddevice, and can be accessed via a wired or wireless network using avariety of communications protocols, and unless otherwise specified, canbe arranged to include a combination of external and internal memorydevices, where such memory can be contiguous and/or partitioned based onthe application.

References to a network, unless provided otherwise, can include one ormore networks, intranets and/or the internet.

Although the methods and systems have been described relative tospecific embodiments thereof, they are not so limited. For example, themethods and systems may be applied to a variety of multirotor vehicleshaving 6, 8, 10, 12, 14, 16, or more independent motor controllers 24and motors, thus providing differing amounts of lift and thus payloadand operational capabilities. The system may be operated under anoperator's control, or it may be operated via network or datalink fromthe ground. The vehicle may be operated solely with the onboard batterystorage capacity, or it may have its capacity augmented by an onboardmotor-generator or other recharging source, or it may even be operatedat the end of a tether or umbilical cable for the purposes of providingenergy to the craft. Obviously many modifications and variations maybecome apparent in light of the above teachings and many additionalchanges in the details, materials, and arrangement of parts, hereindescribed and illustrated, may be made by those skilled in the art.

What is claimed is:
 1. A full-scale, multirotor all-electric aircraftsystem sized, dimensioned, and configured for transporting one or morehuman occupants and payload, the system comprising: a multirotorairframe fuselage, having a structure capable of supporting the totalvehicle weight together with the one or more human occupants andpayload; a lightweight multirotor upper truss structure connected to themultirotor airframe fuselage; a plurality of motor and propellerassemblies attached to the lightweight multirotor upper truss structure,the plurality of motor and propeller assemblies each comprising aplurality of pairs of counter-rotating propeller blades, the pluralityof motor and propeller assemblies being controlled by a plurality ofmotor controllers; an electrical power-generating system comprising oneof: a hydrogen fuel-cell system comprising a hydrogen storage tank, aplurality of fuel cell subsystems, one or more air-driven turbochargerssupplying compressed air to the plurality of fuel cell subsystems, and aplurality of fuel cells supplying voltage and current to the pluralityof motor controllers, wherein the hydrogen fuel-cell system combineshydrogen from the hydrogen storage tank with compressed air to generateelectrical voltage and current; or a motor-generator system comprising afuel storage tank, one or more hydrocarbon-fueled motors, and aplurality of motor-driven high voltage generators to supply current tosaid multirotor motor controllers; a power distribution and circuitbreaker subsystem autonomously monitoring and controlling distributionof the generated electrical voltage and current to the plurality ofmotor controllers and an avionics system; and wherein the plurality ofmotor controllers are commanded by one or more autopilot control units,where the one or more autopilot control units control the commandedelectrical voltage and torque or current for each of the plurality ofmotor and propeller assemblies and track the rotations per minute (RPM)and the torque produced or the current consumed at each of the pluralityof motor and propeller assemblies.
 2. The system of claim 1, wherein asource of power for the plurality of motor and propeller assembliesfurther comprises one or more hydrogen-powered fuel-cells orhydrocarbon-fueled motors with diode or field-effect transistor (FET)isolation between each electrical source and an electrical main bus andthe one or more hydrogen-powered fuel-cells or hydrocarbon-fueledmotors, where each engine may be fueled by compressed natural gas (CNG),liquefied petroleum gas (LPG), or aviation standard fuel (avgas) andeach fuel cell is powered by hydrogen or other suitable gaseous fuel. 3.The system of claim 1, further comprising: an On/Off key connected to ahigh-current contactor that isolates the electrical power-generatingsystem from the plurality of motor and propeller assemblies when powerfrom the electrical power-generating system is not required; a missiondisplay system that displays to an operator information about a state ofperformance metrics of the electrical power-generating system; amotor-enable safety switch providing a means of disabling and enablingthe plurality of motor and propeller assemblies; an external refuelingconnector compatible with infrastructure for electric powered vehicles,to enable aircraft system refueling; a dual display system comprisingapplication software operating on a touch-tablet computer or avionicsdisplay system; a dual mission controller tablet computer comprising theapplication software operating on the touch-tablet computer or theavionics display system, with wired or wireless (RF) connections to theone or more autopilot control units; a wirelessly connected orwire-connected Automatic Dependent Surveillance-Broadcast (ADSB) unitproviding the software application with collision avoidance, traffic,and weather information to and from the multirotor all-electric aircraftsystem; one or more autopilot control units comprising a single-boardcomputer and input/output interfaces comprising at least one of thefollowing interfaces: serial RS232, Controller Area Network (CAN),Ethernet, analog voltage inputs, analog voltage outputs,pulse-width-modulated outputs for motor control, embedded or stand-aloneair data computer capabilities, embedded or stand-alone inertialmeasurement capability, and one or more cross-communication channels ornetworks; a DC-DC converter or starter/alternator configured todown-shift at least a portion of a primary voltage of the multirotorall-electric aircraft system to either 24V or 28V standards for avionicsand non-motor purposes, with a 24V or 28V battery to provide localcurrent storage; a tablet computer operating mission software, or athrottle or foot control pedal, providing a variable voltage orpotentiometer setting indicative of commanded thrust; a tablet computeroperating mission software, or a 2-axis joystick or control yoke,providing two independent sets of variable voltage or potentiometersettings indicative of pitch command and bank command; a means ofcombining pitch, roll, yaw, throttle, and other desired information ontoa serial line, using servo controls, in such a way that multiplechannels of command data pass from tablet to the one or more autopilotcontrol units over the serial line, where control information ispackaged in a plurality of frames that repeat at a periodic rate; theone or more autopilot control units operating control algorithmsgenerating commands to each of the plurality of motor controllers,managing and maintaining vehicle stability, and monitoring feedback. 4.The system of claim 3, wherein the avionics display system for themultirotor all-electric aircraft system comprises an interface to theADSB unit, operable to: receive broadcast data from nearby aircraft;transmit desired state information to the one or more autopilot controlunits to avoid collisions with the nearby aircraft; the one or moreautopilot control units determine an action to command to avoid thecollisions with the nearby aircraft; broadcast position data of themultirotor all-electric aircraft system to the nearby aircraft toprovide the nearby aircraft with the position information to avoidpotential collisions; receive weather data and display the weather dataon the avionics display system; enable operation of the multirotorall-electric aircraft system with no requirement to interact with orcommunicate with air traffic controllers; and perform calculations forflight path optimization and collision avoidance, based upon a state ofthe multirotor all-electric aircraft, states of the nearby aircraft, andavailable flight path dynamics under the National Airspace System orequivalent systems in other countries.
 5. The system of claim 1, furthercomprising controlling the plurality of motor and propeller assembliesto operate the multirotor all-electric aircraft system withinpredetermined aircraft performance limitations.
 6. The system of claim1, further comprising landing skids or wheels connected to themultirotor airframe fuselage supporting the multirotor all-electricaircraft system.
 7. The system of claim 1, wherein the multirotorall-electric aircraft system is controlled within safety, reliability,performance, and redundancy measures necessary to protect human life toaccepted FAA flight-worthiness standards.
 8. The system of claim 1,wherein the plurality of motor controllers are high-voltage,high-current air-cooled or liquid-cooled controllers capable of up to100 kW peak performance minimum.
 9. The system of claim 1, wherein theplurality of motor and propeller assemblies comprise pancake, axial fluxbrushless synchronous three-phase AC or DC brushless electric motors.10. The system of claim 9, wherein the plurality of motor and propellerassemblies are an aircraft motor.
 11. The system of claim 9, wherein theplurality of motor controllers and propeller assemblies provide lift orthrust forces predominantly in the vertical direction.
 12. The system ofclaim 9, wherein pairs of propellers operate in counter-rotatingfashion, so as to produce no net torque to the multirotor all-electricaircraft system, in such a way that a tail rotor is not necessary forstabilized and controlled rotary aircraft operation.
 13. The system ofclaim 12, wherein pairs of the plurality of motor and propellerassemblies can operate at different RPM or Torque settings to produceslightly differing amounts of thrust under computer control, therebyimparting a pitch moment, or a bank moment, or a yaw moment, or a changein altitude, or simultaneously combinations thereof, to the multirotorall-electric aircraft system, using position feedback from on-boardinertial, atmospheric, global positioning system (GPS), and magneticsensors to maintain flight stability.
 14. The system of claim 1, whereinthe multirotor all-electric aircraft system is operable autonomously andwherein some or all of the position and control instructions areperformed outside the multirotor all-electric aircraft system, by usinga broadband or 802.11 Wi-Fi network or Radio Frequency (RF)bidirectional data-link between the multirotor all-electric aircraftsystem and ground-based equipment.
 15. The system of claim 1, whereinthe multirotor all-electric aircraft system is operable autonomously andwherein some or all of the position and control instructions areperformed inside the multirotor all-electric aircraft system, by usingmission planning software to designate a route, destination, andaltitude profile for the multirotor all-electric aircraft system to fly,forming the flight plan for that flight to be performed without humaninvolvement.
 16. The system of claim 1, wherein the electricalpower-generating system further comprises multiple high-current batterycells mounted within modular enclosures of the multirotor airframefuselage that require periodic charging while no in flight, comprising:a battery management system configured to monitor battery voltage,current, charge, and status of the multiple high-current battery cells;and a recharging system compatible with automotive electric vehiclerecharging stations, according to J1772 standards; wherein the multiplehigh-current battery cells are configured to recharge the multirotoraircraft's batteries at an origin, at a destination, or at roadside EVcharging stations; wherein the multiple high-current battery cells areconfigured to operate the multirotor all-electric aircraft system in amanned or unmanned local surveillance mode when ‘tethered’ by a powercable; and wherein the electrical power-generating system uses a portionof the main generated power of the multirotor all-electric aircraftsystem to power onboard avionics through a DC-to-DC converter orstarter-alternator, thereby alleviating a need for separate charger andcharge-ports for batteries powering the onboard avionics.
 17. A methodfor implementing an advanced fault tolerant control of a multirotorall-electric aircraft, comprising: receiving, by at least one validautopilot computing devices communicating over a redundant network, aroute or position command set from dual redundant pilot control tablets;translating, by each available valid autopilot computing devices of theat least one valid autopilot computing devices, the received route orposition command set into output commands to control multiple motorcontrollers, the translating comprising using control algorithms togenerate the output commands for each of the multiple motor controllers;voting on the output commands to be transmitted to the multiple motorcontrollers, by each of the at least three autopilot computing devices,the voting comprising determining which of a majority of the outputcommands of the available valid autopilot computing devices are inagreement; and automatically transmitting the output commands determinedmajority vote to the multiple motor controllers.
 18. The method asclaimed in claim 17, wherein the method further includes the steps of:receiving broadcast data from nearby aircraft; transmitting new outputcommands to the available valid autopilot computing devices to avoidcollisions with the nearby aircraft; broadcasting position data of themultirotor all-electric aircraft to the nearby aircraft; receivingweather data and displaying weather data on an avionics display systemwithin the multirotor all-electric aircraft; enabling operation of themultirotor all-electric aircraft without requiring interaction with orcommunication with air traffic controllers; and performing calculationsfor flight path optimization and collision avoidance, based upon a stateof the multirotor all-electric aircraft, states of the nearby aircraftand available flight path dynamics under the National Airspace System.19. A method for automated flight control and mission planning foroperating a multirotor all-electric aircraft, comprising: a plurality ofautopilot computing devices receiving, from a tablet computing device, aroute or position command set, comprising at least one of physicalmotion and command detected by the tablet computing device or apre-planned mission route pre-programmed into the tablet computingdevice; the plurality of autopilot computing devices measuring and/orreceiving multirotor all-electric aircraft real-time state information;the plurality of autopilot computing devices translating the receivedroute or position command set and the real-time state information intooutputs to control multiple motor controllers of the multirotorall-electric aircraft; the plurality of autopilot computing devicestransmitting the outputs to the multiple motor controllers; theplurality of autopilot computing devices measuring and/or receivingupdated multirotor all-electric aircraft real-time state information;the plurality of autopilot computing devices automatically assessingwhether a new route or position command set is needed to maintainstability of the multirotor all-electric aircraft based on the updatedreal-time state information; and the plurality of autopilot computingdevices transmitting a new route or position command set to the multiplemotor controllers.
 20. The method of claim 19, further comprising:maintaining a specified altitude of the multirotor all-electricaircraft, under command of the tablet computing device and the pluralityof autopilot computing devices; increasing or decreasing an altitude ofthe multirotor all-electric aircraft, under command of the tabletcomputing device and the plurality of autopilot computing devices;maintaining a pitch, bank, and yaw angle of the multirotor all-electricaircraft, under command of the tablet computing device and the pluralityof autopilot computing devices; increasing or decreasing the pitch,bank, and yaw angles independently under command of the tablet computingdevice and the plurality of autopilot computing devices; allowing anoperator to fly a specified origin to destination route by following adisplay presentation; allowing the operator or an unmanned vehicle tofly a pre-programmed origin to destination route and elevation profileby following a pre-programmed mission profile; monitoring availableelectrical and fuel capacity to ensure available flight path dynamicsadequate power remains for performing a flight to the specified originto destination or the pre-programmed origin to destination; andperforming motor control algorithms within the plurality of autopilotcomputing devices.
 21. The method of claim 20, wherein the real-timestate information further comprises reading sensor data and assessingphysical motion and rate of motion by each of the plurality of autopilotcomputing devices to be compared to commanded motion in all threedimensions to assess whether the new route or position command set isneeded.
 22. The method of claim 20, wherein the plurality of autopilotcomputing devices comprise a plurality of autopilot computing devicesand employ voting node techniques to arrive at a majority decision forperforming the motor control algorithms, thereby achieving reliabilityand safety requirements for the multirotor all-electric aircraft andimproving fault tolerance.